


The Sister, The Foster, The Heroine

by Snow_Leopard_777



Category: Batman - All Media Types, DCU, Marvel Cinematic Universe, Miraculous Ladybug, The Flash (TV 2014)
Genre: And my own sadistic mind, I Wrote This Instead of Sleeping, I blame Antique, Just wait and you'll see why >:), Marinette is Jason Todd's sister, Mentor Barry Allen, Mentor Tony Stark, Parental Barry Allen, Protégé Marinette Dupain-Cheng, Sorry Not Sorry, Tags for later :), Tony Stark Acting as Peter Parker's Parental Figure, me too but i wrote it so i deserve it, might bring in more fandoms idk, no death i dont think but there will be major pain for you guys
Language: English
Status: In-Progress
Published: 2021-01-06
Updated: 2021-01-06
Packaged: 2021-03-17 12:54:17
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 2,627
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28600269
Author URL: https://archiveofourown.org/users/Snow_Leopard_777/pseuds/Snow_Leopard_777
Summary: Marinette Catherine Todd Dupain-Cheng was taken off the streets of Gotham as a child and adopted by a visiting family before being taken back to Paris with them. Her life afterwards was an... adjustment, to say the least, but manageable. And after Barry Allen offers to teach her how to be a hero after the Justice League turns her away, she makes friends with people she could have only dreamed of meeting beforehand... Including eventually reuniting with her long-lost brother.
Relationships: Marinette Dupain-Cheng | Ladybug & Team Flash (The Flash TV 2014), Marinette Dupain-Cheng | Ladybug/Damian Wayne
Comments: 35
Kudos: 191





	The Sister, The Foster, The Heroine

**Author's Note:**

> This started out as helping a friend with a prompt, then several of our friends encouraged my madness. Now we are here. Good luck later on, this fic is intended to have a few chapters before the pain begins! ^u^ I, for one, blame Discord.

Marinette Catherine Dupain-Cheng was a force to be reckoned with- it was a well known fact at François-DuPont. Even Chloé Bourgeois knew when to stop pushing. Though some didn't know how vicious the girl could be- those who didn't know her  _ before _ she got control of her temper. Caline Bustier and Principal Damocles did not have the fortune (or misfortune) of knowing Marinette before the Dupain-Cheng's fully assimilated her into the life of a "normal" child. 

Chloé could have told their teacher, especially with Lila at large and quickly wearing on Dupain-Cheng's patience, that asking the girl to welcome and assist an exchange student from Gotham was a  **_Bad Idea™_ ** at the best of times. The girl was a Gothamite, born and bred and straight from the streets, and Chloé was  _ terrified _ of what kind of reaction the girl would have. Bustier may have written over the girl's original personality, but Cathy would  _ never _ be erased. 

Chloé glanced at Sabrina, both girls recognizing it for the opportunity it was. A chance to  _ prove _ to Marinette that they had truly changed for the better. They wouldn't be able to take all the stress off of her, Bustier would have a fit if Marinette wasn't the Gothamite's main caretaker, but they could damn sure make sure the bluenette got frequent breaks and one Damian Prince, host family the Kubdel family, didn't fall prey to a liar or her untrained dogs. 

"Mlle. Bustier. " Alix lazily waved her hand. "Wouldn't it make more sense for me to show the new kid the ropes, he's staying with me anyways."

Seven students watched Caline's eyebrow twitch. Two tried to hide, two prepared for  _ something _ , one prepared to argue, one tried to placate her, and one had a lie about another disability the teacher just  _ had _ to take into consideration right then on the tip of her tongue in less than a millisecond. 

Caline's eyes narrowed slightly as body language shifted. "It's Marinette's job as-"

A loud bang filled the room and Lila let out a pitiful moan. "Mlle, I think my books falling on my bad ankle may have damaged it even more." She offered up her most innocent eyes. "Could you take me to the nurse while Marinette watches the class? I'm sure she can take care of them long enough for you to get me there." Lila made sure her eyes watered, those books were  **heavy** and packed a punch, so it didn't take much. She made one last push when it looked like she was going to object. "Please, I wouldn't want to interrupt the students doing their work."

The teacher caved, shooting Marinette and Alix a look clearly stating the discussion wasn't over before escorting her student to the nurse's office. 

~~~

Damian Wayne was beyond livid. "And I am being forced to play nice with imbeciles beneath my level of education in a school, if the reports are to be believed, constantly under attack of villains, forced to go by a different name, as well as living with unknowns instead of you sending a familial relation with me to Paris why, again?"

Bruce sighed and pinched the bridge of his nose, letting his eyes fall shut for some relief from the constant staring contest. "Aquaman and Wonder Woman both said you would be the best choice after considering the apparent ages of the Parisian heroes. You know how rare it is for them both to agree, so when they do I tend to listen. Especially when Green Lantern also agrees. That has never happened. And, as you said, if the reports are to be believed, better you than Superboy- especially since Superman was the one to originally write those children off. You'll be placed in the "Akuma Class" to observe properly. Evidently only one student in that class has never been akumatized. There is one student who no one remembers the akumazation of because all but three people died instantly."

Damian scowled at his father. Wonder Woman was tolerable enough, he wouldn't object too much on using her name because he did want to remain unknown in Paris. However, being stuck in a class full of fame chasers and coat tail grabbers did not appeal to him in the slightest. Much less being stuck in a  _ house _ with one of them. No, one of his family members and home schooling would do. He'd prefer Alfred, Greyson, or his father, but at this point he'd settle for Todd or Drake. 

Bruce let out a heavier sigh. "Look, Damian. You've traumatized your classmates here. There's a very,  _ very _ small chance of you making even a friendly acquaintance in Gotham. This is a great start. You might even be happier there than here. Able to make a name for yourself beyond being the Blood Son of Bruce Wayne or living in your siblings' shadows." Bruce prayed that, if nothing else, throwing in that bone would tempt his stubborn son. 

Damian bit down on the smirk. His father was running out of arguments. "I'll go. But the minute I consider my mission complete, I shall be on my way home. I will not be summoned by your decree. I will also send a monthly report- you are not to send one of the others to check in on me, nor will you request more than I reveal. Will I be taking the Robin suit?"

Bruce shook his head, "No. Robin is not going on this mission." 

Damina nodded one quick time. "Very well then. Do you agree to my terms?"

Bruce eyed his youngest son. He felt as though there was something he was missing, but the detective could find it later. "Yes."

~~~

Damian smirked as he walked out of the Batcave, pulling out his phone to send a message to 'Awal to be prepared for a hidden Prince of Robins' arrival. They had been waiting for this moment for a while now. Now he only hoped Stark's kids stayed away. Damian <strike>Wayne</strike> Prince had the heart of a princess to win. And he sincerely hoped she didn't tell someone that he was no more than a friend again. 

~~~

**_Two years ago:_ **

_ Ladybug was left with the entire Miraculous Box, Master Fu losing his memories after transferring guardianship to her. She wanted to fall to the ground and scream and cry but she didn't have time. "Make a new team. You need allies. Find them. Recruit them. Fix my worst mistake."  _

_ The girl hid her tears as she left the battle. Her first order of business was to contact anyone she could find to help her. Her first choice was the Justice League. She used her yo-yo to call them. Superman was the one to answer- and the one to turn her away. Panicking, she used Kaalki to teleport to Central City.  _

_ The Flash was beside her in, well, a flash. She watched him fumble when he noticed how young she was. "Kiddo, I don't want to fight you. You're young. I really don't want to have to save you either." _

_ Ladybug blinked. "Excuse me?" Her eyes narrowed in confusion before she processed the fact that they were standing on top of a  _ **_very_ ** _ tall building. "Oh! Non, nothing like that! Monsieur Flash, I need help. Please, is there anywhere private we could talk?"  _

_ "Oh, um… Let me contact my team real quick."  _

_ Ladybug watched him appear on a rooftop three buildings over less than a second later, his hand held against his ear as he spoke with who she assumed were the people who made sure he could be a hero. He was back beside her quickly.  _

_ "Okay, they said to bring you to our base. You'll have to do a scan to make sure you aren't gonna, y'know, blow us up, but that's it. Any dangerous items on you?"  _

_ Ladybug offered a wry smile. "My earrings and sunglasses are ancient magical artifacts that give me superpowers. One allows for teleportation, the other for creation and healing. Dangerous in the wrong hands, yes, but I have been defending my city using mainly my earrings for over a year now. I pose no danger to you." _

_ The Flash blinked. "Okay then." Less than a millisecond later they were speeding through the streets. Ladybug gawked at S.T.A.R. Labs, amazed at the size and complexity of it.  _

_ Ladybug allowed them to do the scans they wanted. The magick of the Miraculous would keep anything that would allow her identity to be compromised from being processed properly. She took Kaalki's glasses off once they finished and stored them in her yo-yo, relaxing as the constant drain on her energy lessened.  _

_ She looked at the two scientists, detective, and pair of siblings standing in the room and took a deep breath. "My name is Ladybug. My partner and I have been protecting Paris on our own for a little over a year. The Guardian chose us to protect our city, but now the Guardian is gone. He passed his role on to me in our last battle and we have no one to turn to for help. Hawkmoth is becoming bolder, he's manipulating and akumatizing more and more people and we can't fight without help. Our teammates were compromised, their identities exposed, and I don't know what to do. I tried calling Justice League headquarters, but Superman turned me away, he said I should be more respectful of the seriousness calling the Justice League means. But if Hawkmoth were to claim the Miraculi of myself and my partner and combine them… there is no telling what would happen. The Miraculous are about balance, and his wish could cause the world to end as we know it and rewrite itself. He could wipe out an entire civilization and no one would know what happened. So please, tell me, what can I do? _

_ The room gaped at her even as Barry Allen's mind raced. "You reverse the damage the fights cause, don't you? That's where there's not a recorded increase of deaths or structural damage in Paris. And if you fix everything, your partner must destroy. You're needed to keep Paris whole, your partner has to be active for you to be active. You cancel each other out and keep catastrophe from striking." _

_ Ladybug nodded. "Thymescrica used only the Ladybug Miraculous, now the Amazons are basically immortal unless felled in battle. The Mayans used only the Black Cat Miraculous, their entire civilization disappeared without a trace." _

_ "So you need help and a true mentor. Not just a Guardian who helps when he decides to." Ladybug hung her head, unable to contest The Flash's words. "My name is Barry West-Allen. The people you see here are my family. The man who raised me as his own, Joe West, his daughter and my wife, Iris West-Allen, my brother in law, Wally West, my best friends and pseudo siblings Caitlyn Snow and Cisco Ramon, and my biological dad, Henry Allen, isn't here. We're going to help you and train you. You won't be left to try to fight on your own. I'll also try to get into contact with the hero kids and see if they won't be willing to help. You said something about akumatized? What's that?" _

_ "Hawkmoth has the Butterfly Brooch. He uses little akumas, purplish black butterflies, to turn people into supervillains. They aren't fully in control of their actions and never remember what happened to them. But their powers vary. They might just be able to fight us and destroy things, or they might be able to control civilians or turn things into their own army. Bring about natural disasters and even become our perfect copies. His partner, Mayura, is a newer player, she has the Peafowl Pin. She makes Senti-monsters using amoks, feathers that turn a normal object into a living monster that does whatever the akumatized or amokitized victim wants or what they think is best for them. Whoever gets the Senti-monster's charm will be able to control them. Which means they can work with us instead of against us. There was a senti-monster made in my image once, she only survived Mayura taking the amok away because we saw she wasn't a monster. I gave her the charm that would control her and let her make her own decisions- and I showed her how to use the magickal storage space in the Ladybug's yo-yo, Mayura's magic couldn't penetrate it. She lives with me and is known as my cousin, Bridgette." _

_ Caitlyn Snow stepped forward. "Your scans… you shouldn't be alive right now, much less able to walk. Your bones have been fractured so many times… they're held together by glowing colors, several different ones. What are they?" _

_ Ladybug bowed her head. "My cure only goes so far when it comes to healing myself. Everyone else gets a full recovery but I do not. I have scars from each time the cure had to heal me- and most of the healing was done by the Kwamis. Their magick is what has kept me from being permanently damaged." _

_ Cisco Ramon sucked in a sharp breath. "Your suit is magic. I can't help with that… but. What you need isn't just training, the major players in the Justice League, and even the Avengers, need to be kept far away from Paris. You don't need to fight any of them if they get akumatized. If you reveal your identity to us, Barry can come collect you and your partner for training a couple times a week… if you're okay with that. Because if not that's cool too and we can figure something else out." _

_ Ladybug shook her head. "I can reveal my identity as long as you promise you don't come to Paris and get super upset. But my partner won't be able to join us. He has too many responsibilities as a civilian." Ladybug took a deep breath and looked at Kaalki. The little horse nodded in agreement. "T-tikki. Spots off."  _

_ Joe almost broke the chair he was holding when he saw how young the girl was. He had to deal with both his sons being crime fighting metas, even possibly his grandchild once they were born and grew up, but they would have guidance and restrictions placed to where they would be unable to fight crime until they were at least sixteen. The girl standing in front of him couldn’t have been any older than twelve. “How old are you?” The words were out of his mouth before he even comprehended saying them.  _

_ The girl blinked at him, obviously surprised. “I just turned thirteen about a month ago, why?” _

_ Joe bit his tongue, the child was obviously traumatized, no need for him to attack the one person that she had been depending on for however long she’d been combating this villain.  _

_ The girl took a deep breath. “My name is Marinette Dupain-Cheng. I am thirteen years old and have been fighting as the superheroine Ladybug for over a year now. I was eleven, nearly twelve, when I first received my miraculous and I have had no official training. Please, if you are willing to help, help me.” _

_ Barry hid his eyes for a second, he knew the look on her face, it was one he’d seen many times. The look of someone accustomed to being given hope and having it ripped away. “Of course I’ll help. I’ll contact the kids associated with the JLA, convince their mentors that I want to teach them something or another and have them come train with you. We won’t leave you.” _

_ He thought she was going to start crying when her eyes misted over, but all she did was bow and offer a very heartfelt “Thank-you.” _

**Author's Note:**

> Link for my Discord that I forgot in the last post XD: https://discord.gg/rSen8M2TbA


End file.
